From animals to humans: The spread of viruses

A closer look at some of the deadly viruses that have jumped from animals to humans

HIV

The HIV virus (colourised)

The Human Immunodeficiency Virus is thought to have originated in non-human primates. Studies have shown and suggested that human hunting of said primates allowed the virus to transfer over in the mind-20th century. WHO estimates that there are now 36.7million people living with AIDS globally.

SARS

People were advised to wear masks during the SARS outbreak

Severe Acute Respiratory Syndrome emerged in China in 2002, wiping out a population of 800 humans before it was contained. Authorities culled thousands of civet cats when they found a link between the outbreak and a virus strain in the cats.

Depending on the severity of the strain of the virus, the Ebola haemorrhagic fever can kill 95 percent of infected people. The recent outbreak in 2013-1016, was termed as an emergency outbreak by WHO The disease has taken a large toll on the gorilla populations in Central Africa, even though the virus is said to have been hosted by fruit bats. As of 29 March, 2016 the virus was no longer declared as an emergency.

Nipah virus

A colourised grab of the nipah virus

From a bat to pigs to humans. The Nipah virus has certainly had a long journey. Harboured by fruit bats, this virus in Malaysia found its way to humans via infested pigs in 1999. In pig farms, groves of fruit trees were frequently visited by fruit bats, which defecated into pigpens. Infected pigs then passed the virus to farmers, causing over 100 deaths.

Dengue fever

Like malaria, dengue fever is transmitted from mosquitoes to humans. There are an estimated 40 million cases around the world every year, resulting in thousands of deaths. Symptoms include severe fevers, headaches, and muscle and joint pains.

Bird Flu

The H5N1 Asian strain of bird flu is highly pathogenic, deadly to birds and can cause disease and death in humans. Almost all infected are the people who have been in direct contact with fowls, mainly those involved in the poultry industry. The virus strain cannot jump from human to human. The most recent case would be in Delhi India, where birds were culled in the Delhi Zoo, to prevent the strain from spreading to other animal enclosures.

Zika Virus

A 3D rendition of the Zika virus

The Zika virus, named after the Zika forest, Uganda from where it originated, is a mild form of fever, much like dengue fever. Primates are suspected to be the original hosts of the virus, which can spread to humans either by a mosquito, sexual intercourse, blood transfusion or during pregnancy from the mother to foetus. This can result in the baby being born with severe brain deformity and other birth defects. While there is no prescribed medicine, paracetamol and bed rest are practiced treatment. As of 2016, there is no vaccine for the Zika virus.